1. Field of the Invention
This invention relates to a connector for a transmission cable and, in particular, to a connector having a contoured conductive shell thereon adapted to provide an impedance control function in the transition region where the conductors of the cable are joined to the contacts of the connector.
2. Description of the Prior Art
A transmission cable connector is an electrical connector component adapted to interconnect each electrical conductor of a cable to a respective complementary contact. The structure of the cable is meticulously designed and fabricated so that the electrical characteristics of the cable (including impedance and crosstalk) may be precisely controlled.
Such cables, which may be in round or flat form, are typically interconnected to other circuit components using a transmission cable connector. In the case of a round cable the interconnection is usually made by first fanning the extending ends of the cable into a generally planar array and securing each of the wires of the individual conductors to the respective contacts provided in the connector. The interconnection between the extending conductors and the contacts may be directly made, as by solder.
In some instances the center-to-center spacing of adjacent conductors in the planar array of conductors is different than the center-to-center spacing of the contacts in the connector. In such a case a transition circuit board is provided. The transition circuit board is a generally planar substrate having an array of conductive tracings with termination pads formed at each end of each tracing. Such tracings and pads may be disposed on one or both of the surfaces of the substrate. The individual conductors of the cable are suitably secured to the input pads along one edge of the transition board while the contacts of the connector are soldered into contact with output pads provided along other of the edges of the substrate. Typically the entire connector assembly is surrounded by a plastic housing.
In the typical case little if any consideration is given to the electrical characteristics of the transition region between the ends of the cable and the contacts in the connector, whether or not an intermediate transition board is provided. It is often assumed that the electrical length of the transition region is electrically too short to cause problems with data transmission. However, this is not always true. At higher frequencies the signal transmission benefits, particularly the impedance and crosstalk considerations resulting from precise design of the cable, are lost when one neglects the electrical characteristics of the conductors, contacts and board in the transition region.
Accordingly, in view of the foregoing, it is believed advantageous to provide a transmission cable connector which includes an impedance control arrangement in the transition region between the cable and the connector.